Abstract
Ceramide, the central molecule of the sphingomyelin pathway, serves as a second messenger for cellular functions ranging from proliferation and differentiation to growth arrest and apoptosis. In this study we show that c2-ceramide induces apoptosis in primary cortical neuron cultures and that this effect correlates with differential modulation of mitogen-activated protein kinase (MAPK) cascades. Phosphorylation of extracellular signal-regulated kinases (ERKs) and their upstream activators MAPK kinases (MEKs), as measured by immunoblotting is rapidly decreased by c2-ceramide. However, the MEK inhibitor PD98059 alone does not induce apoptosis and in combination with c2-ceramide it does not modify c2-ceramide-induced apoptosis. Treatment with c2-ceramide increases p38 and c-Jun N-terminal kinase (JNK) phosphorylation before and during caspase-3 activation. The p38 inhibitor SB203580 partially protects cortical neurons against c2-ceramide-induced apoptosis, implicating the p38 pathway in this process. The c2-ceramide treatment also increases levels of c-jun, c-fos and p53 mRNA in primary cortical neuron cultures, but this is independent of p38 activation. Our study further elucidates the time-courses of MAPK cascade modulation, and of c-jun, c-fos and p53 activation during c2-ceramide-induced neuronal apoptosis. It reveals that one of the activated kinases, p38, is necessary for this apoptosis.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Apoptosis / drug effects
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Apoptosis / physiology*
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Cell Survival / drug effects
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Cell Survival / physiology
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Cells, Cultured / cytology
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Cells, Cultured / drug effects
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Cells, Cultured / enzymology
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Ceramides / metabolism*
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Ceramides / pharmacology
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Cerebral Cortex / cytology
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Cerebral Cortex / drug effects
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Cerebral Cortex / enzymology*
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Down-Regulation / drug effects
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Down-Regulation / physiology
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Enzyme Inhibitors / pharmacology
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Fetus
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Imidazoles / pharmacology
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MAP Kinase Signaling System / drug effects
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MAP Kinase Signaling System / physiology*
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Mice
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Mitogen-Activated Protein Kinase 8
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Mitogen-Activated Protein Kinases / drug effects
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Mitogen-Activated Protein Kinases / metabolism*
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Neurons / cytology
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Neurons / drug effects
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Neurons / enzymology*
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Phosphorylation / drug effects
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Proto-Oncogene Proteins c-fos / genetics
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Proto-Oncogene Proteins c-jun / genetics
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Pyridines / pharmacology
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RNA / drug effects
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RNA / metabolism
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Sphingomyelins / metabolism
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Sphingosine / analogs & derivatives
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Sphingosine / pharmacology
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Tumor Suppressor Protein p53 / genetics
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Up-Regulation / drug effects
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Up-Regulation / physiology
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p38 Mitogen-Activated Protein Kinases
Substances
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Ceramides
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Enzyme Inhibitors
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Imidazoles
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N-acetylsphingosine
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Proto-Oncogene Proteins c-fos
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Proto-Oncogene Proteins c-jun
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Pyridines
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Sphingomyelins
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Tumor Suppressor Protein p53
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RNA
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Mitogen-Activated Protein Kinase 8
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Mitogen-Activated Protein Kinases
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p38 Mitogen-Activated Protein Kinases
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Sphingosine
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SB 203580